Technology of fabrication and electrical characteristics of W, Mo, Ni and Ir, Pd contacts with YBa₂Cu₃O_7-x

The technology of fabrication and the properties of metallic electrical contacts on ceramics of YBa₂Cu₃O_7-x superconductors have been studied. Contacts were deposited using the method of metal-organic chemical vapour deposition (MOCVD) for Ir, Pd and the method of exploding wires for W, Mo, Ni. The contacts, prepared by evaporation of Ir in oxygen atmosphere, have specific contact resistance rho _c of about 10^-5 Omega cm². Since the temperature of deposition of contacts is 300-400 degrees C (i.e. lower than 500 degrees C, the temperature at which chemical interaction on the YBa₂Cu₃O_7-x-Si, SiC, SiO₂ boundary starts), such a technique can be incorporated into silicon-compatible technologies. It has been shown that good adhesion and specific contact resistivities of approximately 10^-2 Omega cm² for W and Ni and approximately 10^-3 Omega cm² for Mo can be achieved. After subsequent annealing rho _c reaches 10^-6, 7*10^-5, 7*10^-3 and 10^-2 Omega cm² for Ir, Ni, W and Mo, respectively.